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opus_rc: add entropy encoding functions

Browse Source 
Mostly used the RFC document, the decoding functions and
the reference encoder's implmenentation as a reference.

Signed-off-by: Rostislav Pehlivanov <atomnuker@gmail.com>
pull/148/merge
Rostislav Pehlivanov 8 years ago
parent 8fa18e042a
commit 373ee2c618
2 changed files with 212 additions and 5 deletions
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  1. 182
      libavcodec/opus_rc.c
  2. 35
      libavcodec/opus_rc.h

182
libavcodec/opus_rc.c
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@ -1,7 +1,7 @@
/*
* Copyright (c) 2012 Andrew D'Addesio
* Copyright (c) 2013-2014 Mozilla Corporation
* Copyright (c) 2016 Rostislav Pehlivanov <atomnuker@gmail.com>
* Copyright (c) 2017 Rostislav Pehlivanov <atomnuker@gmail.com>
*
* This file is part of FFmpeg.
*
@ -29,6 +29,21 @@
#define OPUS_RC_BOT (OPUS_RC_TOP >> OPUS_RC_SYM)
#define OPUS_RC_SHIFT (OPUS_RC_BITS - OPUS_RC_SYM - 1)
static av_always_inline void opus_rc_enc_carryout(OpusRangeCoder *rc, int cbuf)
{
const int cb = cbuf >> OPUS_RC_SYM, mb = (OPUS_RC_CEIL + cb) & OPUS_RC_CEIL;
if (cbuf == OPUS_RC_CEIL) {
rc->ext++;
return;
}
rc->rng_cur[0] = rc->rem + cb;
rc->rng_cur += (rc->rem >= 0);
for (; rc->ext > 0; rc->ext--)
*rc->rng_cur++ = mb;
av_assert0(rc->rng_cur < rc->rb.position);
rc->rem = cbuf & OPUS_RC_CEIL; /* Propagate */
}
static av_always_inline void opus_rc_dec_normalize(OpusRangeCoder *rc)
{
while (rc->range <= OPUS_RC_BOT) {
@ -38,6 +53,16 @@ static av_always_inline void opus_rc_dec_normalize(OpusRangeCoder *rc)
}
}
static av_always_inline void opus_rc_enc_normalize(OpusRangeCoder *rc)
{
while (rc->range <= OPUS_RC_BOT) {
opus_rc_enc_carryout(rc, rc->value >> OPUS_RC_SHIFT);
rc->value = (rc->value << OPUS_RC_SYM) & (OPUS_RC_TOP - 1);
rc->range <<= OPUS_RC_SYM;
rc->total_bits += OPUS_RC_SYM;
}
}
static av_always_inline void opus_rc_dec_update(OpusRangeCoder *rc, uint32_t scale,
uint32_t low, uint32_t high,
uint32_t total)
@ -48,6 +73,20 @@ static av_always_inline void opus_rc_dec_update(OpusRangeCoder *rc, uint32_t sca
opus_rc_dec_normalize(rc);
}
/* Main encoding function, this needs to go fast */
static av_always_inline void opus_rc_enc_update(OpusRangeCoder *rc, uint32_t b, uint32_t p,
uint32_t p_tot, const int ptwo)
{
uint32_t rscaled, cnd = !!b;
if (ptwo) /* Whole function is inlined so hopefully branch is optimized out */
rscaled = rc->range >> ff_log2(p_tot);
else
rscaled = rc->range/p_tot;
rc->value += cnd*(rc->range - rscaled*(p_tot - b));
rc->range = (!cnd)*(rc->range - rscaled*(p_tot - p)) + cnd*rscaled*(p - b);
opus_rc_enc_normalize(rc);
}
uint32_t ff_opus_rc_dec_cdf(OpusRangeCoder *rc, const uint16_t *cdf)
{
unsigned int k, scale, total, symbol, low, high;
@ -67,6 +106,11 @@ uint32_t ff_opus_rc_dec_cdf(OpusRangeCoder *rc, const uint16_t *cdf)
return k;
}
void ff_opus_rc_enc_cdf(OpusRangeCoder *rc, int val, const uint16_t *cdf)
{
opus_rc_enc_update(rc, cdf[val], cdf[val + 1], cdf[0], 1);
}
uint32_t ff_opus_rc_dec_log(OpusRangeCoder *rc, uint32_t bits)
{
uint32_t k, scale;
@ -84,6 +128,12 @@ uint32_t ff_opus_rc_dec_log(OpusRangeCoder *rc, uint32_t bits)
return k;
}
void ff_opus_rc_enc_log(OpusRangeCoder *rc, int val, uint32_t bits)
{
bits = (1 << bits) - 1;
opus_rc_enc_update(rc, (!!val)*bits, bits + !!val, bits + 1, 1);
}
/**
* CELT: read 1-25 raw bits at the end of the frame, backwards byte-wise
*/
@ -105,6 +155,27 @@ uint32_t ff_opus_rc_get_raw(OpusRangeCoder *rc, uint32_t count)
return value;
}
/**
* CELT: write 0 - 31 bits to the rawbits buffer
*/
void ff_opus_rc_put_raw(OpusRangeCoder *rc, uint32_t val, uint32_t count)
{
const int to_write = FFMIN(32 - rc->rb.cachelen, count);
rc->total_bits += count;
rc->rb.cacheval |= av_mod_uintp2(val, to_write) << rc->rb.cachelen;
rc->rb.cachelen = (rc->rb.cachelen + to_write) % 32;
if (!rc->rb.cachelen && count) {
AV_WB32(rc->rb.position, rc->rb.cacheval);
rc->rb.bytes += 4;
rc->rb.position -= 4;
rc->rb.cachelen = count - to_write;
rc->rb.cacheval = av_mod_uintp2(val >> to_write, rc->rb.cachelen);
av_assert0(rc->rng_cur < rc->rb.position);
}
}
/**
* CELT: read a uniform distribution
*/
@ -127,6 +198,16 @@ uint32_t ff_opus_rc_dec_uint(OpusRangeCoder *rc, uint32_t size)
return k;
}
/**
* CELT: write a uniformly distributed integer
*/
void ff_opus_rc_enc_uint(OpusRangeCoder *rc, uint32_t val, uint32_t size)
{
const int ps = FFMAX(opus_ilog(size - 1) - 8, 0);
opus_rc_enc_update(rc, val >> ps, (val >> ps) + 1, ((size - 1) >> ps) + 1, 0);
ff_opus_rc_put_raw(rc, val, ps);
}
uint32_t ff_opus_rc_dec_uint_step(OpusRangeCoder *rc, int k0)
{
/* Use a probability of 3 up to itheta=8192 and then use 1 after */
@ -142,6 +223,14 @@ uint32_t ff_opus_rc_dec_uint_step(OpusRangeCoder *rc, int k0)
return k;
}
void ff_opus_rc_enc_uint_step(OpusRangeCoder *rc, uint32_t val, int k0)
{
const uint32_t a = val <= k0, b = 2*a + 1;
k0 = (k0 + 1) << 1;
val = b*(val + k0) - 3*a*k0;
opus_rc_enc_update(rc, val, val + b, (k0 << 1) - 1, 0);
}
uint32_t ff_opus_rc_dec_uint_tri(OpusRangeCoder *rc, int qn)
{
uint32_t k, scale, symbol, total, low, center;
@ -166,6 +255,23 @@ uint32_t ff_opus_rc_dec_uint_tri(OpusRangeCoder *rc, int qn)
return k;
}
void ff_opus_rc_enc_uint_tri(OpusRangeCoder *rc, uint32_t k, int qn)
{
uint32_t symbol, low, total;
total = ((qn>>1) + 1) * ((qn>>1) + 1);
if (k <= qn >> 1) {
low = k * (k + 1) >> 1;
symbol = k + 1;
} else {
low = total - ((qn + 1 - k) * (qn + 2 - k) >> 1);
symbol = qn + 1 - k;
}
opus_rc_enc_update(rc, low, low + symbol, total, 0);
}
int ff_opus_rc_dec_laplace(OpusRangeCoder *rc, uint32_t symbol, int decay)
{
/* extends the range coder to model a Laplace distribution */
@ -205,6 +311,30 @@ int ff_opus_rc_dec_laplace(OpusRangeCoder *rc, uint32_t symbol, int decay)
return value;
}
void ff_opus_rc_enc_laplace(OpusRangeCoder *rc, int *value, uint32_t symbol, int decay)
{
uint32_t low = symbol;
int i = 1, val = FFABS(*value), pos = *value > 0;
if (!val) {
opus_rc_enc_update(rc, 0, symbol, 1 << 15, 1);
return;
}
symbol = ((32768 - 32 - symbol)*(16384 - decay)) >> 15;
for (; i < val && symbol; i++) {
low += (symbol << 1) + 2;
symbol = (symbol*decay) >> 14;
}
if (symbol) {
low += (++symbol)*pos;
} else {
const int distance = FFMIN(val - i, (((32768 - low) - !pos) >> 1) - 1);
low += pos + (distance << 1);
symbol = FFMIN(1, 32768 - low);
*value = FFSIGN(*value)*(distance + i);
}
opus_rc_enc_update(rc, low, low + symbol, 1 << 15, 1);
}
int ff_opus_rc_dec_init(OpusRangeCoder *rc, const uint8_t *data, int size)
{
int ret = init_get_bits8(&rc->gb, data, size);
@ -226,3 +356,53 @@ void ff_opus_rc_dec_raw_init(OpusRangeCoder *rc, const uint8_t *rightend, uint32
rc->rb.cachelen = 0;
rc->rb.cacheval = 0;
}
void ff_opus_rc_enc_end(OpusRangeCoder *rc, uint8_t *dst, int size)
{
int rng_bytes, bits = OPUS_RC_BITS - opus_ilog(rc->range);
uint32_t mask = (OPUS_RC_TOP - 1) >> bits;
uint32_t end = (rc->value + mask) & ~mask;
if ((end | mask) >= rc->value + rc->range) {
bits++;
mask >>= 1;
end = (rc->value + mask) & ~mask;
}
/* Finish what's left */
while (bits > 0) {
opus_rc_enc_carryout(rc, end >> OPUS_RC_SHIFT);
end = (end << OPUS_RC_SYM) & (OPUS_RC_TOP - 1);
bits -= OPUS_RC_SYM;
}
/* Flush out anything left or marked */
if (rc->rem >= 0 || rc->ext > 0)
opus_rc_enc_carryout(rc, 0);
rng_bytes = rc->rng_cur - rc->buf;
rc->waste = (size - (rc->rb.bytes + rng_bytes)) << 3;
memcpy(dst, rc->buf, rng_bytes);
memset(dst + rng_bytes, 0, FFMAX(rc->waste >> 3, 0) + 1);
/* Put the rawbits part, if any */
if (rc->rb.bytes || rc->rb.cachelen) {
int rawbytes = FFALIGN(rc->rb.bytes*8 + rc->rb.cachelen, 8) >> 3;
int dst_loc = FFMAX(size - rawbytes, 0);
uint8_t *src = rc->buf + OPUS_MAX_PACKET_SIZE + 12 - rawbytes;
ff_opus_rc_put_raw(rc, 0, 32 - rc->rb.cachelen);
dst[dst_loc] |= *src++;
memcpy(&dst[dst_loc + 1], src, rawbytes - 1);
}
}
void ff_opus_rc_enc_init(OpusRangeCoder *rc)
{
rc->value = 0;
rc->range = OPUS_RC_TOP;
rc->total_bits = OPUS_RC_BITS + 1;
rc->rem = -1;
rc->ext = 0;
rc->rng_cur = rc->buf;
ff_opus_rc_dec_raw_init(rc, rc->buf + OPUS_MAX_PACKET_SIZE + 8, 0);
}

35
libavcodec/opus_rc.h
Unescape View File

@ -1,7 +1,7 @@
/*
* Copyright (c) 2012 Andrew D'Addesio
* Copyright (c) 2013-2014 Mozilla Corporation
* Copyright (c) 2016 Rostislav Pehlivanov <atomnuker@gmail.com>
* Copyright (c) 2017 Rostislav Pehlivanov <atomnuker@gmail.com>
*
* This file is part of FFmpeg.
*
@ -26,6 +26,8 @@
#include <stdint.h>
#include "get_bits.h"
#define OPUS_MAX_PACKET_SIZE 1275
#define opus_ilog(i) (av_log2(i) + !!(i))
typedef struct RawBitsContext {
@ -41,6 +43,15 @@ typedef struct OpusRangeCoder {
uint32_t range;
uint32_t value;
uint32_t total_bits;
/* Encoder */
uint8_t buf[OPUS_MAX_PACKET_SIZE + 12]; /* memcpy vs (memmove + overreading) */
uint8_t *rng_cur; /* Current range coded byte */
int ext; /* Awaiting propagation */
int rem; /* Carryout flag */
/* Encoding stats */
int waste;
} OpusRangeCoder;
/**
@ -72,14 +83,30 @@ static av_always_inline uint32_t opus_rc_tell_frac(const OpusRangeCoder *rc)
}
uint32_t ff_opus_rc_dec_cdf(OpusRangeCoder *rc, const uint16_t *cdf);
void ff_opus_rc_enc_cdf(OpusRangeCoder *rc, int val, const uint16_t *cdf);
uint32_t ff_opus_rc_dec_log(OpusRangeCoder *rc, uint32_t bits);
uint32_t ff_opus_rc_dec_uint(OpusRangeCoder *rc, uint32_t size);
void ff_opus_rc_enc_log(OpusRangeCoder *rc, int val, uint32_t bits);
uint32_t ff_opus_rc_dec_uint_step(OpusRangeCoder *rc, int k0);
void ff_opus_rc_enc_uint_step(OpusRangeCoder *rc, uint32_t val, int k0);
uint32_t ff_opus_rc_dec_uint_tri(OpusRangeCoder *rc, int qn);
void ff_opus_rc_enc_uint_tri(OpusRangeCoder *rc, uint32_t k, int qn);
uint32_t ff_opus_rc_dec_uint(OpusRangeCoder *rc, uint32_t size);
void ff_opus_rc_enc_uint(OpusRangeCoder *rc, uint32_t val, uint32_t size);
uint32_t ff_opus_rc_get_raw(OpusRangeCoder *rc, uint32_t count);
void ff_opus_rc_put_raw(OpusRangeCoder *rc, uint32_t val, uint32_t count);
int ff_opus_rc_dec_laplace(OpusRangeCoder *rc, uint32_t symbol, int decay);
void ff_opus_rc_enc_laplace(OpusRangeCoder *rc, int *value, uint32_t symbol, int decay);
int ff_opus_rc_dec_init(OpusRangeCoder *rc, const uint8_t *data, int size);
void ff_opus_rc_dec_raw_init(OpusRangeCoder *rc, const uint8_t *rightend, uint32_t bytes);
int ff_opus_rc_dec_init(OpusRangeCoder *rc, const uint8_t *data, int size);
void ff_opus_rc_dec_raw_init(OpusRangeCoder *rc, const uint8_t *rightend, uint32_t bytes);
void ff_opus_rc_enc_end(OpusRangeCoder *rc, uint8_t *dst, int size);
void ff_opus_rc_enc_init(OpusRangeCoder *rc);
#endif /* AVCODEC_OPUS_RC_H */

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